Which of the following species is neither hypervalent nor hypovalent ? — Chemical Bonding Chemistry Question

💡 Solution & Explanation

Step 1: A hypovalent species has fewer than 8 valence electrons around its central atom, while a hypervalent species has more than 8 valence electrons. Step 2: Analyze each species: ClO4^- has Chlorine expanding its octet (hypervalent); BF3 has Boron with only 6 valence electrons (hypovalent); SO4^2- has Sulfur with 12 valence electrons in its common resonance structures (hypervalent). Step 3: In the carbonate ion (CO3^2-), the central Carbon atom forms three sigma bonds and one pi bond, satisfying the octet rule perfectly with exactly 8 valence electrons. Thus, it is neither hypervalent nor hypovalent, matching option (d).